Software, Internet, and Networks Explained

Posted on Nov 16, 2024 in Computers

Software Types

Free Software

Loosely used, distributed, and copied by those with the same purpose, for which the encoder source is made available.

Unfree Software

Authorizes use to license holders. The license requires payment and grants rights to the author. The software shall not be altered or distributed.

Shareware

Distributed for evaluation with limited validity.

Freeware

A free license is issued, and it can be freely scheduled by users. The source code may or may not be known. If known, users cannot modify it.

Public Domain Software

Distributed free and without a license for non-profit use.

Demos

A test version that expires after a certain time.

Internet

Origins

Started as a military communications network.

Information Transfer

1. Each file is divided into packets. Each packet follows an independent route to reach the destination.
2. Routers return packets that are not for them and rebuild the desired file from the received packets.

Communication Protocols

1. TCP: Code used to assemble and reconstruct files.
2. IP: Unique personal address for each computer and internet connection.

Internet Service Providers (ISPs)

Provide IP transit.

Permanent Connections (DRSC) / Static IP

1. Public Switched Telephone Network (PSTN)
2. Modem Conversion: A/D/A

Access to Resources and Platforms

1. E-commerce: The process of buying and selling services from order to customer delivery and payment.
2. Distance Education (e-learning)

Network Hardware

Switch

Connects multiple network devices (computers). Serial ports connect more devices. This device generates and holds a table in memory to select the recipient of the information.

Hub

Does not generate a table and has no memory. Sends the signal to all ports; does not select the recipient. Technologically less advanced.

Transmission Media and Associated Hardware

1. Twisted Pair Cable: 4 pairs of independently woven threads (UTP), each end with an RJ45 connector.
2. Wireless: Wireless network card and a wireless access point (switch that collects wireless signals and distributes them across the network).

Hardware for Internet Connection

1. Modem: Converts digital and analog signals to be sent via telephone lines.
2. Router: Connects local area networks, the network switch, and the internet.

Network Protocols

A set of rules that specify data exchange.

Network Protocols Provided by Windows XP

1. NetBEUI: For Windows 95 and NT, used for local area networks without communication with other local networks.
2. IPX/SPX: Built for Microsoft, supports Novell NetWare.
3. TCP/IP: 5 layers:
   • Level 5 (Application: used for displaying web content, transferring files, etc.)
   • Level 4 (Transport)
   • Level 3 (Network)
   • Level 2 (Data Link)
   • Level 1 (Physical: electrical aspects)

IP Addresses

A sequence of 4 numbers separated by dots, each containing a value between 0 and 255.

Types of IP Address Ranges

1. Class A: Range: 0.0.0.0-127.0.0.0, Mask: 255.0.0.0
2. Class B: Range: 128.0.0.0-191.255.0.0, Mask: 255.255.0.0
3. Class C: Range: 192.0.0.0-223.255.255.0, Mask: 255.255.255.0

Network Computing

A set of interconnected computers that allows sharing resources (hardware and software).

Advantages of Networks

Sharing videos, sharing information, user control, security, faster and safer copies.

Types of Networks

PAN (Personal Area Network – a few meters), LAN (Local Area Network – classrooms), CAN (Campus Area Network – various buildings), MAN (Metropolitan Area Network), WAN (Wide Area Network – different countries).

Network Connection

Allows linking a computer to an existing network or the internet. Each network card connected to a computer has a network connection.

Wireless Networks

Wireless local area networks (WLANs) are characterized by their transmission medium, which is the air, with substantial cable savings.

Major Wireless Network Topologies

1. Infrared: Allows point-to-point communication between two devices through infrared LED emitter-receivers. Drawbacks include low transfer rate and the need for direct line of sight.
2. Bluetooth: Connects wireless devices for personal use. Allows integration of the device within a local area network and access to their memory. Transmission speed is 400 Kbytes/s, and the range reaches 10-20 meters.
   • PIM File Transfer: Allows exchange of data such as calendar notes and contacts.
   • File Transfer: Performs file operations in a directory.
   • Network Access: Allows sharing the connection to the network.
   • Serial Ports: Allows remote devices to connect wirelessly.
   • Audio Gateway: Allows remote devices like speakers and microphones to work.
   • Headset: Lets other devices use input and output devices that are not their own.
3. Wi-Fi: System with the ability to connect wirelessly using radio waves.

Wireless Connections

1. Ad Hoc: Point-to-point connections between wireless devices, usually used for two computers to communicate with each other.
2. Infrastructure Mode: Communication through wireless cards with an access point as an intermediary.

Network Security

Firewall

Filters information, blocking unknown or insecure software. A security barrier that verifies information, reducing or permitting access depending on its configuration.

Making a Network Cable: Order

Green striped, green, orange striped, blue, blue striped, orange, brown striped, brown.

Digital Images

Obtained through a scanner or digital camera and stored in bits.

Pixel

Units that make up a digital image. The color of a digital image is made up of pixels. Each pixel can have an indeterminate number of different colors. Pixel depth is measured in bits.

Image Types

• Bitmap: One bit per pixel, black or white.
• Grayscale: 8 bits per pixel, 256 gray levels.
• Indexed Color: One channel with 8 bits per pixel, 256 colors.
• RGB: Red, green, and blue. 3 channels with a depth of 24 bits per pixel, 16.7 million colors.
• CMYK: Cyan, magenta, yellow, and black. 4 channels with 32 bits per pixel. Used in printing.
• HSB: Hue (color), Saturation (purity of color), Brightness (intensity).

Image Resolution

Number of pixels per unit area. Printed resolution is typically 72 pixels per inch. Common screen resolutions include 640×480, 800×600, 1024×768, and higher. Greater resolution means smaller pixels and higher image definition.

Digital Image Formats

Bitmap Formats

• BMP: High quality but large file size.
• TIFF: For high-quality images that will be printed.
• XCF: Native GIMP format, supports layers.
• PICT: Characteristic of the Mac platform.
• JPG: Most widely used format on the internet due to small file size, but loses quality when compressed.
• GIF: Lossless compression, supports animation.
• PNG: Combines advantages of JPG and GIF.

Image Compression Formats

• RLE: Lossless, supported by Windows.
• LZW: Supported by GIF and TIFF.
• JPEG: Lossy, best results for photographs.

Vector Image Formats

• WMF: Widely used on computers.
• SWF: Vector animation for web pages.
• EPS: Used for exporting images.
• PDF: Compatible between Mac and PC platforms.

Network Computing (Additional Information)

When two or more computers are connected and exchange information. Connecting several computers allows building a small computer network. The most common technology used in small networks is the star topology, where all cables connect to a central point.

Network Components

• Network Card: Intermediary between the network and the computer.
• Network Card Driver: Software that instructs the network card.
• Shared Network Program: Installed on one computer and used by other computers on the network.
• Network Database: Stores information from all connected computers.
• Server: Provides a service.
• Specialized Server: Similar to regular computers but with higher quality components.

Wireless Connections (Additional Information)

Point-to-point connections between two wireless devices are often used for two computers to communicate with each other.

Modem

Connects a single computer to the internet.